TABLE 1.
Imaging the ultrastructure of cell surface layersa
| Organism | Sample | Immobilization procedure | Observationsb | Reference |
|---|---|---|---|---|
| Bacillus coagulans | S-layer | Covalent linkage to glass/mica | Oblique lattice; r ≅ 10 nm (study of antibody binding) | 36 |
| Recrystallization on silanized silicon | Oblique lattice; r = 1-2 nm (agreement with electron microscopy) | 39 | ||
| Bacillus sphaericus | S-layer | Covalent linkage to glass/mica | Square lattice; r ≅ 12 nm (agreement with electron microscopy) | 36 |
| Recrystallization on silanized silicon | Square lattice; r = 1-2 nm (agreement with electron microscopy) | 39 | ||
| Recrystallization on supported lipid bilayers | Square lattice; r = 1-2 nm (novel S-layer/lipid bilayer structures) | 49 | ||
| Bacillus stearothermophilus | S-layer | Recrystallization on various silicon surfaces | Oblique lattice; r ≅ 1.5 nm (study of recrystallization process) | 38 |
| Deinococcus radiodurans | Hexagonally packed intermediate layer | Covalent linkage to glass | Ring-shaped hexamers; r = 1 nm (correlation with electron microscopy) | 21 |
| Adsorption on mica | Conformational change of central pores | 29 | ||
| Adsorption on HOPG | Tapping mode; r = 1-1.5 nm | 25 | ||
| Halobacterium halobium | Purple membrane | Adsorption on mica, silanized glass, and supported lipid bilayers | Hexagonal symmetry; r = 1.1 nm | 11 |
| Halobacterium salinarum | Purple membrane | Adsorption on mica | Conformational changes; r < 1 nm | 31 |
| Tapping mode; r = 1-1.5 nm | 25 | |||
| Trigonal lattice; r = 0.5 nm (antibody labeling; complementarity with X-ray and electron crystallography) | 35 | |||
| Escherichia coli | Porin OmpF | Assembly on mica in the presence of lipids | Porin trimers; r = 1 nm (comparison with X-ray structure; detection of two conformations) | 42 |
| Voltage and pH-dependent conformational changes | 32 | |||
| Escherichia coli | Aquaporin Z | Assembly on mica in the presence of lipids | Tetramers; p42(1)2 and p4 symmetry, r < 1 nm (proteolytic cleavage force-induced conformational changes) | 43 |
a
Survey of AFM studies reviewed in this paper; not an exhaustive list.
b
r values are lateral resolution determined directly from the images or after image processing.